1. Field of the Invention
The present invention relates to interior lighting utilizing natural lighting fixtures. In particular, the invention concerns a skylight enclosure adapted to receive solar light and distribute the received light to selected areas of a building interior.
2. Description of Related Art
The idea of converting a skylight dome in one""s roof to a more useful item that will effectively distribute light and illuminate desired areas of an interior, has resulted in the creation of a wide variety of elaborate and complicated solar lighting systems. For example, U.S. Pat. No. 5,099,622 discloses a roof mounted skylight from which extends a tubular structure that terminates about flush with the ceiling of a room. The domed portion of the skylight extending above the roof is transparent and includes a reflector. The reflector captures a portion of sunlight that would otherwise pass through the dome and directs it into the underlying tubular structure. The reflected light exits the structure through a concave diffuser which scatters the captured light throughout a room.
The above system is inefficient because all light entering the tubular structure can only exit through the downward facing diffuser. Therefore, no matter how concave the diffuser is, there will still be dark areas around the room. Additionally, the reflector will also shield some of the sunlight during certain times of every day. As a result, less sunlight will enter the structure causing diminished illumination.
U.S. Pat. No. 5,175,967 seeks to overcome the above deficiency by placing a reflective surface at an inner lower terminal end of the tubular housing. The mirror is positioned at a 45xc2x0 angle to direct light through a window placed in the side of the housing. An objection to this arrangement is that the mirror itself blocks out a substantial portion of light that could otherwise be directed out of the bottom of the structure. Thus, while light is directed out one portion of the housing, the area directly beneath the structure is severely deficient in illumination. Further, the side window through which reflected light exits, has no means for adjustment or for inhibiting sunlight glare.
A more sophisticated passive lighting system using a glass dormer structure for a roof is shown in U.S. Pat. No. 5,408,795. This elaborate system allows light to pass through openings in the glass dormer and become softened and diverted by passing through layers of diffusers, mirrors and fresnel lens panels. A primary function of the system is to enable an inside person to view outdoor images, while also dispersing ambient daylight. This, of course, results in lower amounts of overall illumination and defeats the purpose of most skylight assemblies.
A significant attribute of the present invention is the ability to enhance light captured in a solar lighting enclosure and transmit the light out the sides of the enclosure in a controlled manner without glare and with minimal loss to the light intensity. The system provides a housing having light reflecting interior surfaces between a light admitting top opening and a light emitting bottom opening. The enclosure includes a lower wall portion within which is incorporated light directing means comprising side extraction panels through which light, collected from within the enclosure, passes outwardly in predetermined directions.
One or more side extraction panels may be used depending on the location of the interior building areas to be illuminated. When the system is used to illuminate hallways or aisles, the side extraction panels can be positioned on sides of the enclosure that face the above areas.
If even more light is desired for specific work areas or selected decorative areas of a room, the side extraction panels may be provided with light guide means incorporated into the panels to direct light specifically to those areas. Conversely, if more indirect lighting is desired, the guide means can transmit light toward a reflective ceiling. The panels may also be equipped with tilt adjustment mechanisms for rotating the panels away from the enclosure lower wall portion. This permits light to be directed at a more downwardly inclined angle than is possible with internal guide means.
In cases where it is more important to direct most of the light outwardly through the side extraction panels, the interior of the enclosure may be provided with light control means. The light control means transmits a portion of the enclosure light to an underlying diffuser while simultaneously reflecting other portions of the light toward the side extraction panels. The light control means may comprise flat, curved or fluted light control partitions that are sized to be equal to, or less than, the entire area of the enclosure light emitting bottom opening. More than one partition may be used and each partition may be fixed in place or be rotatable.
The light control partitions may also have varying shapes such as triangular, polygonal, round, oval and trapezoidal. Still further, as with the side extraction panels, the light control partitions may be equipped with angular adjustment means such as slotted brackets, pawl and rachet assemblies, piston/shaft air or hydraulic devices, jack screw and related apparatus known in the art. When the size and shape of the light control partitions are coordinated, they may operate together to create variable sized open areas to allow light to pass unobstructed out the enclosure bottom light emitting opening. This feature may be used to delineate emitted light patterns for special illumination needs.
The efficiency of the overall system is improved by utilizing a light collimator over the enclosure light admitting top opening. This will allow better alignment and reflection of the light rays within the enclosure and will diminish the effects of sun glare. It is also advantageous to provide a light diffuser sheet over the light emitting bottom opening to further reduce glare and to enhance the distribution of light in a downward direction.